help...low 02s and knock

[turbocvc]

Ok guys I can't seem to figure this out. I've had my car for over a year now and slowly getting it up and running like it should on a very small budget...meaning $50 here, $25 here, $100 here...etc. No charging plastic unless I have the cash to pay for it. Anyways, the car is a stock setup 87 GN. So far I've added 42 lb injectors with TT 91 octane chip, a Walbro pump, adjustable regulator, fuel pressure gauge, scanmaster, new plugs and wires, fuel filter, changed all vacuum hoses, fixed the speedo gear and govenor gear so now it reads MPH. Before it ran like a turd, it would pull until 10# and flatten out. After replacing the fuel pump with the walbro, it was a totally different car. But now its knocking like crazy and I can't seem to get the o2 readings up above 700 The boost is currently set at 14#, fuel pressure is set at 46# with vac off. The chip was burnt for 17# of boost with I believe 18* timing. 1st and 2nd gear show no knock but as soon as it hits 3rd o2 readings would sometimes be 003 - 675 and thats after I have raised the fuel through the chip to 9.4% more. Knock was reading from 2 - 10, I have yet to make a full 3rd gear blast I know I need a hotwire kit, thats next on the list but I verified fuel pressure is rising with boost and not dropping. The o2 sensor is a bosch and its only a year old with maybe 4 months driving time on it. Here are my scanmaster readings in idle after about 10 mins of driving.

AF - 04
L8 - 30
BAT - 13.2
INT - 128
BL - 135
CLT - 182
ATS - 132
R - 800
TPS - .44
IAC - 25
CC - 97

o2 readings at idle is 750

Let me know what you think

 

[QUIP'6']

get a hot wire on there and report back before you blow it up. or maybe you all ready have!!!!

 

[DailyDrifter]

running like it should on a very small budget...meaning $50 here, $25 here, $100 here...etc.

Thats impossible , seriously . Sounds like your fuel pump isnt up to the task. Like was said before me get a hotwire kit AND a fuel pump. Dont blow it up or you cant throw your budget right out the window.

 

[turbocvc]

I know, I know, there's no such thing as a small budget when it comes to cars...been there multiple times. And yes the hotwire will be ordered this weekend. The pump is brand new with less than 200 miles on it. What I'm getting at is why the o2 are still low while fuel pressure is up with the boost, so I know its getting proper fuel pressure and the pump is still good. The only thing the hotwire is going to do is maintain a constant voltage to the pump so fuel pressure doesn't drop as it hits boost...or is there something else I'm missing.

 

[Underboost]

Q:Has the motor ever been out and is it a TT chip?

 

[GNRick]

I would put an AC Delco O2 sensor on it. Can you replay the scanmaster readings after a run? If so you might see O2 volts dropping out when they should be increasing. Same goes for TPS.

 

[Underboost]

I would put an AC Delco O2 sensor on it. Can you replay the scanmaster readings after a run? If so you might see O2 volts dropping out when they should be increasing. Same goes for TPS.

+1

 

[DailyDrifter]

The pump might not be pushing enough volume at WOT. Put the hot wire in.

 

[Underboost]

Also check with a 15mm wrench the 2 bolts on the back of the Passenger side Head. This wiring has been a problem before. Car ran great but the O2's would not pass 670 at wot. TPS,Fuel Reg,Pump,Hot Wire,Alky all worked fine. All because a half turn on one bolt.

Not saying this is it but don't single it out.

 

[turbocvc]

As far as I know the motor hasn't been out, has 107k on it now. The chip is a TurboTweak. As far as the tps readings at WOT during a run its showing 4.10, with car off its reading 4.20. After a quick run the recall on the scanmaster will show the lowest o2 readings which it showed 003 o2 and 6* KR. Keep in mind I'm letting off as soon as I see knock so I haven't been able to get a full read at top of 3rd. 1st and 2nd is fine, another quick run showed only 675 o2 and 8* kR. I just ordered a Denso o2 sensor hoping that would help as I read that another memeber switched from a Bosch to a Denso and his readings went up

 

[GNRick]

I once bought a Bosch before I knew better. The thing wouldn't even screw into the bung.

 

[XLR8]

You stated you have a FP gauge. You need to see what FP does as the O2's start to drop. If the FP does not rise 1# for every 1# of boost then you do not have enough fuel volume. If the FP rises then you can look elsewhere for the problem.

 

[bosted86]

i had a similar problem and found a small break in the vacuum line going to the fpr. replaced it and problem was gone. worth a check i guess.

 

[turbocvc]

Yeah fuel pressure is rising with boost 1:1, I just replaced all vacuum lines and got rid of the plastic vacuum line connecting to the fuel pressure regulator and replaced it with a tight fitting silicone line. I didn't replace the check valves, maybe I need to check and replaces those too. Anyways I'm gonna tinker with it tonight and check the bolts behind passenger head as mentioned above.

 

[Underboost]

Have you tried turning the fuel psi down to 43psi and setting the chip to default. You could also see a lean reading on the O2's do to a very,very rich condition.

 

[turbocvc]

Well still waiting on hotwire kit, in the meantime I dropped in a new denso o2 and my readings at idle improved 800+ but same results at wot. I have tried lowering fuel pressure and resetting the chip with no luck...that was on the old o2 sensor. I'll try doing the same with new one to see if there are any improvements.

 

[turbocvc]

So hotwire is installed, fuel pressure set to 43 line off, reset the chip to default, new denso o2...still o2 readings are low at wot and won't go pass 675?? Boost is only set at 13-14, vacuum lines replaced, fuel pressure is rising with boost...WTF? Could I have a header crack somewhere, would that cause a lean o2 reading?